1. Technical Field
The present invention relates to a metal magnetic powder and a method for forming the same, and more particularly, to a metal magnetic powder capable of improving a direct current (DC)-bias characteristic and an inductance property of an inductor, a method for forming the same, and an inductor manufactured using the metal magnetic powder.
2. Description of the Related Art
A multilayer type power inductor is mainly used in a power supply circuit such as a direct-current (DC) to direct-current (DC) converter within a portable electronic device, and in particular, the inductor materially or structurally suppresses magnetic saturation thereof to be used at a high current. The multilayer type power inductor has a disadvantage in that a change in inductance value according to a current applied thereto is large, however, has an advantage in that it has a smaller size and a thinner thickness as compared to a wire-wound type power inductor, thereby being appropriate for the recent trend of electronic components.
The multilayer type power inductor is manufactured by multilayering magnetic sheets having internal electrodes printed thereon to manufacture a device body, and then forming external electrodes electrically connected to the internal electrodes on each surface at both ends of the device body. Here, the magnetic sheets are generally made of a composite material containing a ferrite powder. In addition, in order to decrease the change in inductance with respect to the current at an outer portion, a gap layer made of a non-magnetic material may be inserted into the device body to cut a magnetic flux.
In the above-described power inductor, a soft magnetic material having good reactivity even in a low magnetic field is used in order to implement a high inductance characteristic, wherein a ferrite powder has been used as the soft magnetic material. However, the power inductor using the soft magnetic material such as ferrite is difficult to implement excellent DC-bias characteristics due to a material limitation in a saturation magnetic flux. Therefore, technology for manufacturing a power inductor by using a metal magnetic powder having a high saturation magnetic value using the soft magnetic material has been recently developed.
However, in the case of the metal magnetic powder, a phosphate salt, or the like, which is a non magnetic insulator, is used as an insulation coat for the surface, but the thus-prepared phosphate coating film has a weak heat resistance, or the like, and can be easily destroyed in the preparation thereof, such that resistance characteristic is remarkably deteriorated by a heat treatment at a high temperature of about 500 or more, and a loss in an eddy current is increased.